O− detected by ESR as a radiation-induced electron-excess defect in KClO3

A family of ESR spectra from KClO3 crystals irradiated with x rays at 26 K are assigned to electron-excess defects consisting of O− ions trapped in different environments, which may be identified because the electron spin on O− polarizes the adjacent ions. In the primary configurations, O− is associated with ClO−2. Secondary configurations, in which O− is trapped between two ClO−3 ions, arise from a thermally activated substitution process of the Grotthuss type: leading to migration of the excess negative charge along the crystallographic axis a. The O− defects in KClO3 are structurally very similar to those observed earlier in irradiated KClO4. As in KClO4, O− reacts with O2 at ∼230 K to yield O−3.